All of the changes you make in Firefox, like your home page, what toolbars you use, extensions you have installed, saved passwords and your bookmarks, are all stored in a special folder, called a profile. Your profile folder is stored in a separate place from the Firefox program so that, if something ever goes wrong with Firefox, your information will still be there. It also means you can uninstall Firefox without losing your settings and you don't have to reinstall Firefox to clear your information or troubleshoot a problem.
Click the menu button , click help and select Troubleshooting Information. The Troubleshooting Information tab will open.